Many anti-abortion activists believe that human life and, therefore, pregnancy begin when the human egg is fertilized and that standard birth control pills cause abortions by keeping the fertilized egg from implanting in the womb. This isn’t the general theory on either count. The American College of Obstetricians and Gynecologists defines pregnancy as beginning with the fertilized egg’s implantation.
ACOG is a highly politicized, untrustworthy organization. Anyway, what does Collins think the “general theory” is? That the “fertilized egg” is not alive? Is it dead or inanimate, then? That it is not human? Then to what species does it belong? Embryological textbooks tend to say things like, “a new, genetically distinct human organism is formed when the chromosomes of the male and female pronuclei blend in the oocyte.” Maybe their authors are pro-life fanatics too.